The present disclosure relates generally to wellbore operations and, more particularly, to systems and methods to efficiently harvest fluid energy or mechanical energy imparted to a drillstring in a wellbore using preloaded magnetostrictive elements.
Power for use in a downhole environment in the past has generally been either stored in a device, such as a battery, and conveyed downhole or generated downhole by an alternator driven, such as by the flow of drilling mud, or it has been transmitted via conductors, such as a wireline, from the earth's surface or another remote location. As is well known, batteries have the capability of storing only a finite amount of power therein and have environmental limits, such as temperature, on their use.
Electrical conductors, such as those in a conventional wireline, provide a practically unlimited amount of power, but require special facilities at the surface for deployment and typically obstruct the production flowpath, thereby preventing the use of safety valves, limiting the flow rate of fluids through the flowpath, etc. while the conductors are in the flowpath. Thus, wireline operations are typically carried out prior to the production phase of a well, or during remedial operations after the well has been placed into production.
In wellbore operations, it is desirable to provide one or more efficient power sources downhole, for example, to power downhole instrumentation. A wide variety of fluids may be used in downhole operations and may be pumped artificially or flow naturally through numerous tubing structures. Existing downhole generators—such as an alternator driven by mudflow, as mentioned earlier—are limited in that they cannot operate at whatever speed is dictated by the fluid flow, because doing so would produce too much power, causing a heat build-up which may damage electrical components. Additionally, existing downhole generators cannot be optimized during operation to maximum power generation when operating conditions change. What is needed is a method for efficiently generating electrical energy from downhole energy sources using a variable and optimizable generator.
While embodiments of this disclosure have been depicted and described and are defined by reference to exemplary embodiments of the disclosure, such references do not imply a limitation on the disclosure, and no such limitation is to be inferred. The subject matter disclosed is capable of considerable modification, alteration, and equivalents in form and function, as will occur to those skilled in the pertinent art and having the benefit of this disclosure. The depicted and described embodiments of this disclosure are examples only, and not exhaustive of the scope of the disclosure.